The invention relates to bleaching regulator (stabiliser) compositions for bleaching with H.sub.2 O.sub.2, which contain gluconic acid, nitrilotriacetic acid and magnesium in ionic form, which furthermore may be accompanied by a content of citric acid. Such bleaching regulators are employed in aqueous solution which has been rendered alkaline.
Naturally occurring plant fibres, such as cotton, sisal, jute and the like, contain, in the crude form, waxes, fats and other plant constituents which cause a yellowish-brown colouring of the fibre. As a result, not all the desired dyeings are possible; moreover the dyeing results are unlevel. These fibres are therefore subjected to a treatment in which bleaching and washing are combined, in order to remove the undesirable non-fibrous constituents and to destroy the substances which cause the yellowish-brown colouring. Such a treatment can be applied on the fibres of the origin mentioned, on yarns produced therefrom and on woven fabric, knitted fabric or nonwovens of such fibres. This treatment furthermore can be applied on mixtures of such fibres with synthetic fibres and products produced therefrom.
So-called bleaching liquors which comprise water, hydrogen peroxide, wetting agents/detergents and emulsifiers, alkali to adjust the pH and H.sub.2 O.sub.2 regulators (stabilisers) are employed for carrying out the combined treatment mentioned. Sodium Silicate and inorganic phosphates, for example, have been employed as regulators for a long time. Because of excessive fertilisation of the waste waters, the inorganic phosphates were later replaced by (poly)phosphonates. However, these phosphonates are difficult or even impossible to degrade, and thus pollute the waste waters again in a different manner. The non-biodegradable ethylenediaminetetraacetic acid (EDTA), which moreover is not absorbed by sewage sludge, is also unacceptable in its use as an H.sub.2 O.sub.2 regulator. With EDTA, moreover, remobilisation of heavy metals is not completely excluded.
There was therefore a desire to provide completely phosphorus-free and EDTA-free bleaching regulators (stabilisers). However, development has shown to date that it does not seem possible to dispense with phosphates or phosphonates or EDTA in such regulators.